how are head phone amps connected to your hi fi for example the graham slee nova - i am guessing they would be connected to the audio outs on your amp? do they have both an audio in and out built in - reason for my question is i only have one set of outputs on my pre amp which go to two mono power amps that have no outputs - would i need to buy a splitter or are the boxes designed with this in mind? if they have an in and out would i notice any reduction in sound quality?